Power supply plug in missing part

@justincabana that looks like a detachable Duckhead 2 prong plug. Those are designed for dual voltage (Input: 100-240V 50/60Hz) and by just changing the prong plug the same power supply can be used around (most of) the world. That way it gets cheaper to manufacture.

I have not seen the part being sold separately but I would check where travel adapters (maybe they have it for the Valve VR) are being sold. They may just offer those parts. Otherwise you may need to check places like Ebay (used one) or even Aliexpress etc.

If you absolutely have no luck in finding one, get an adapter like this and add one of these and you are back in business with a working power supply. These are just examples and definitely not endorsements.